docs: def get_lexer_for_mimetype(_mime, **options):
      """Get a lexer for a mimetype.
  
      Raises ClassNotFound if not found.
      """
      for modname, name, _, _, mimetypes in itervalues(LEXERS):
          if _mime in mimetypes:
              if name not in _lexer_cache:
                  _load_lexers(modname)
              return _lexer_cache[name](**options)
      for cls in find_plugin_lexers():
          if _mime in cls.mimetypes:
              return cls(**options)
      raise ClassNotFound('no lexer for mimetype %r found' % _mime)